A New Selective Cleavage of N,N-Dicarbamoyl-Protected Amines Using Lithium Bromide

Abstract

A mild and new procedure for the selective cleavage of an alkoxycarbonyl group (Boc, CBz) in N,N-dicarbamoyl-protected amino compounds is described. The method is based on the use of lithium bromide in acetonitrile and is compatible with a large range of other functionalities present in the substrates. Compared with other reported methodologies, the procedure is particularly useful for the Cbz-selective cleavage in N,N-Ts,Cbz-diprotected amines. A rationalization of the selectivity supported by ab initio calculations is also presented.

Synthesis of 5‐Cyano‐Tryptophan as a Two‐Dimensional Infrared Spectroscopic Reporter of Structure

“…[11] This reaction sequence has been performed on a scale to provide greater than 5 g of 4 (See SI). Selective removal of one Boc-group from the bis-Boc-carbonate with Mg(ClO 4 ) 2 [15] and hydrolysis of the methyl ester with LiOH, afforded ( S )- N α -Boc- N (in) -Boc-5-cyano-tryptophan ( 1 ) suitable for peptide synthesis. Exchange of the Boc-protecting group on the N -terminus for an Fmoc-group [16], was achieved through a 4-step route starting with 4 (41% over 4 steps).…”

Functional group tolerance in BTB-based metal–organic frameworks (BTB – benzene-1,3,5-tribenzoate)

“…Direct single protection of the amino groups was not possible synthetically. Therefore, two Boc protecting groups were first introduced per amino group and afterward one of these groups was removed selectively, using the method developed by Martin et al [41] (for more details see Supplementary data S1).…”

Synthesis of new chiral 2-functionalized-1,2,3,4-tetrahydroquinoline derivatives via asymmetric hydrogenation of substituted quinolines

“…Thus, the cleavage of one Boc residue of 14 was performed in the presence of lithium bromide at 65 C for 1 h, furnishing 13 in 89% yield after purification. 20 The complete deprotection of 14 into 15 was carried out in acidic ethanol with 90% yield. Then, 2-aminomethylquinoline 12 was obtained in 82% yield from reaction of 15 with sodium hydroxide.…”